I'm relatively new to Mac and I cannot for the life of me figure out why it is so complicated to download an OS installer, create a bootable disk and use it on another machine.

According to the official Apple documentation here, one must:

El Capitan downloads as a disk image. On a Mac that is compatible with El Capitan, open the disk image and run the installer within, named InstallMacOSX.pkg. It installs an app named Install OS X El Capitan into your Applications folder. You will create the bootable installer from this app, not from the disk image or .pkg installer.

I downloaded the 6 GB file. But when I run the installer, I get a message saying

This version of OS X 10.11 cannot be installed on this computer.

But I am not trying to install it on this computer! I want to install it on a different computer!

How do I just get the OS image so I can create the bootable drive to use in the other machine?

I really appreciate your advice!

  • What OS is your other iMac running? Can't you move the installer to it?
    – lhf
    Apr 21, 2020 at 12:18
  • The other iMac has no OS currently. It goes straight to the recovery screen Apr 21, 2020 at 14:17
  • 1
    Why not do recovery then? BTW, which iMac model is it?
    – lhf
    Apr 21, 2020 at 14:21
  • 1
    Does it have to be El Capitan? Dependent to your iMac model, you can install the default Mac OS X version. Just start your computer, and immediately press and hold cmd + r . This will make you enter to recovery mode. Then you will see a list of options. One of them is an installation option for the most recent (dependent on your iMac version) mac os x. Then you only need internet connection. It will install everything smoothly. Apr 21, 2020 at 14:22
  • Because when I try to do it that way, I connect to the internet but then get an error message "A required download is missing" There's a discussion here that leads nowhere (discussions.apple.com/thread/250807649) , so I wanted to try reinstalling it from a bootable drive Apr 21, 2020 at 15:04

2 Answers 2


Given that you have the IntallMacOSX.pkg file you need to extract the app -so, you want this answer: How can I open a .pkg file manually?

You can then extract the "Install OS X El Capitan.app" application into your Applications directory and proceed with the steps as outlined by Apple.

  • 2
    I managed to do it with pkgutil --expand InstallMacOSX.pkg macos-install. But then inside macos-install, there is no .app file as you describe. There is only Distribution, [yet another] InstallMacOSX.pkg, and a folder called Resources Apr 21, 2020 at 4:38

I moved this answer to earlier duplicate question.

  • Does it really have to be 16GB? The download size is less than 6GB Apr 21, 2020 at 16:22
  • I am not sure. This link is an image of a Get Info window for the 16 GB flash drive I used. The on disk use was 7.6 GB. Beginning a 8 GB flash drive will actually hold sightly less than 8 GB, I do not know if all the data will fit. Also, this may depend on the brand of flash drive you use. Apr 21, 2020 at 18:19
  • @CodyBugstein: I updated my answer. Let me know, if you still have questions about step 2. Apr 21, 2020 at 22:41
  • Thanks David! Got it. Now I'm stuck on the second phase of this whole saga. Would you be able to take a look here: apple.stackexchange.com/questions/389087/… ? Apr 22, 2020 at 1:54
  • In the erase dialogue I get, I don't get the "Scheme" option. Is that a problem ? Apr 23, 2020 at 6:11

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